Incandescent electric lamp.



PATENTED FEB. 14, 1905.

J. H. GUEST.

INGANDBSGBNT ELECTRIC LAMP.

APPLICATION FILED MAY 14. 1904.

ATTORNEYS Patented February 14, 1905.

PATENT OFFICE.

JOHN H. GUEST, OF BROOKLYN, NEIV YORK.

INCANDESCENT ELECTRIC LAMP.

SPECIFICATION forming part of Letters Paten N0- 782,749, dated February14, 1905.

Application filed May 14, 1904. Serial No. 207,890.

To all whom it may concern Be it known that I, J GEN H. GUEs'r, aeitizenof the United States, and a resident of Brooklyn, in the county of Kingsand State of New York, (with post-office address 223 Schermerhornstreet, Brooklyn, New York,) have invented certain new and usefulImprovements in Incandescent Electric Lamps, of which the following is aspecification.

My invention relates to electric lamps, such as incandescent lamps,which as now ordinarily constructed have their leading-in wires madewholly or partially of platinum at the point where they pass through theglass seal.

The general object of my invention is to cheapen the cost of productionof such lamps by substituting copper or other cheap metal for the moreexpensive metal platinum.

A further object of the invention is to dispense with the use of fusedjoints, such as are employed in the seal, when for the sake of cheapnessthe leading-in wire is made of a short piece of platinum wire secured tocopper wire.

Heretofore in this art it has been the practice to make that portion ofthe leading-in wire which is sealed in the glass wholly or partly ofplatinum, which metal, although an expensive metal, has heretofore beenuniformly used, because it has been deemed impossible to make a goodseal without using a metal whose coeificient of expansion is the same orapproximately the same as that of the glass. possible to use aleading-in wire which within the glass seal is entirely of copper orother cheap metal whose coefficient of expansion is very different fromthat of the glass in which it is sealed.

My invention consists, first, of a leading-in wire which at some pointwithin the seal has an offset or deviation from the straight line of themain portion of the wire, thus compensating for or eliminating theeffects of the contraction or expansion of said main portion, suchoffset portion being preferably highly attenuated or of much reducedcrosssection as compared with the main portion, which is of suflicientsize to afford the desired mechanical support to the parts.

By my invention, however, it becomes.

My invention consists, further, of a leading-in wire which at some partthereof within the glass seal is attenuated or of reduced cross-section,said reduced and contiguous unreducod portion being integral and beingboth sealed in the glass.

In carrying out my invention I prefer to subdivide the leading-in wireinto two or more conductors at the offset or attenuated portion thereof,in which case the two subdivisions springing from the main portion ofthe wire would constitute a loop in the form of a ring, oval or othershape, depending upon the curve or form of each offset.

By making the conductor highly attenuated I greatly reduce the liabilityto a defective seal due to lateral expansion of the conductor. The highdegree of attenuation which it is possible to employ for this purpose isdue to the fact that in the case of copper especially its conductivityis extremely high, being approximately six times that of platinum, sothat the conductor may be reduced in cross-section or highly attenuatedand yet be capable of carrying the required amount of current for thefilament.

The process of manufacturing the leadingin wire to give it the requiredform may obviously be greatly varied.

In the accompanying drawings I illustrate one method that may be usedwhen my improved leading-in wire is manufactured from ordinary copperwire.

Figure 1 shows a piece of ordinary copper wire as it appears previouslyto the first step in the process. Fig. 2 shows the same as fiattened outat the first stage in the process of manufacture. Fig. 3 shows aleading-in wire constructed in accordance with my invention in thepreferred form. Fig. 4 shows the same as sealed in the lamp. Fig. 5shows a modification.

The wire, Fig. 1, having been flattened out by pressure and preferablyin a mold to form a disk, as indicated in Fig. 2, of considerable area,said disk may be placed in a punch or press and punched to produce theloop shown in Fig. 3, each side of which loop is of any desired form andof much reduced area in crosssection as compared with the main orunsubdivided portion of the wire. As will be seen, each side is offsetfrom the main portion and is hence not affected by the contraction ofsuch main portion. I do not limit myself to any particular degree ofattenuation or reduction of the cross-section in the conductor formingthe offset or sides of the loop, but in general prefer to make the sameas small as possible consistent with the ability of the conductor tocarry the current without undue heating.

For an ordinary sixteen-candle-power lamp the said cross-section ofreduced area may be equivalent to that of a round wire .063 millimetersin diameter.

The leading-in wire, formed as shown, is sealed in the glass of the lampby compressing the glass while in fused condition around said wire and.as indicated at 3, Fig. 4, so that the seal shall embrace both the mainportion of the conductor and the attenuated portion or portion ofreduced cross-sectional area. The seal is established and maintained atsuch attenuated and offset portion of the wire.

The contiguous portions of the conductor 1, around which the glass isalso compressed, are firmly anchored or supported in the glass, and thecontraction and expansion, if it should interfere with the integrity ofthe seal around such larger portions, will not destroy the mechanicalsupport, while at the same time the seal is insured by the close andcontinued union between the glass and the contiguous finer section orsections.

IVhile the integrity of the seal may be attributed to the fact thatthere is an offset in the wire which relieves a part from the efi'ectsof linear expansion in the main portion of the wire, it may also beattributed to the fact that the smaller portion is of such smallcross-section that its total amount of contraction and expansion isexceedingly small, and whatever contraction takes place is practicallyfollowed up or compensated for by the elasticity of the glass in whichit is embedded. In other words, by making the wire at this pointsufiiciently thin or attenuated, which I am able to do because of itshigh conductivity, the difference in the cocfiicient of contraction andexpansion of the glass and the copper is fully compensated for.

While I have specified copper as the material because of its cheapnessand high conductivity, I do not limit myself to the use thereof, butinclude in my claims any metal which is substantially like copper inthat it has a coefficient of expansion different from glass incontradistinction to platinum, heretofore selected and used because ithas substantially the same coeflicient of expansion, and in that it has,like copper, a high degree of conductivity, permitting it to be greatlyattenuated and yet be able to carry suificient current to supply thefilament with the requisite amperage.

It is obvious that the subdivision of the conductor into a number ofbranches is useful in contributing to the result, since each 'is thenrequired to carry a portion only of the current and may therefore bemade finer than would be the case if one conductor only were used.

I am aware that it has been proposed before to make a leading-in wireout of a number of strands or separate wires sealed in the glass; but inall such previous cases the separate strands have projected from theglass and have been united by soldering, twisting, or otherwise to themain portion of the said leading-in conductor.

As indicated in Fig. 5, the conductor may be subdivided into three wiresor conductors each of smaller cross-section, this being secured by apunch of suitable form operating on the flattened disk 2 or by any otherdesired manipulation of the leading-in conductor to secure a sectionwhich shall be of very fine wire, there being preferably, however, amultiplicity of said sections or subdivisions.

What I claim as my invention is 1. In an incandescent electric lamp, aleading-in wire which, within the glass seal, is of reducedcross-section, said reduced portion and contiguous unreduced portionbeing integral with one another and being both sealed in the glass ofthe lamp.

2. An incandescent electric lamp, having a leading-in wire composedwholly of copper and having a portion attenuated or reduced incross-section as described, said attenuated portion and contiguousunreduced portions being integral and being both sealed in the glass ofthe lamp as and for the purpose described.

3. In an incandescent electric lamp, a leading-in wire subdivided into anumber of finer wires integral therewith. the said subdivided portionand contiguous undivided portion being sealed together in the glass ofthe lamp.

4. An incandescent electric lamp having a leading-in wire, a section orportion of which within the glass seal consists of an attenuated ring orloop.

5. An incandescent electric lamp having a leading-in wire which at someportion within the glass seal consists of a loop integral with the mainportion of said leading-in wire which projects from the seal.

6. In an incandescent electric lamp a leading-in wire having an offsetwithin the glass seal as and for the purpose described.

7. In an incandescent lamp a leading-in wire having an attenuated offsetwithin the glass seal.

Signed at New York, in the county of New York and State of New York,this 11th day of May, A. D. 1904.

JOHN H. GUEST. W'itnesses:

C. F. TIsenNnR, J r., ANNA B. TALLMAN.

